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Selecting a content management system takes some forethought. Do you have any particular requirements that need to be served?

http://www.cmsmatrix.org/
has a massive list of available cms options that you can compare against each other. I wouldn't suggest most of them for company use, but they do cover Stellent, Joomla, Drupal, etc..

There are a few systems, such as Joomla & Drupal, that will work quite well for smaller organizations.

On the other hand, look into Oracle UCM (formally Stellent), Documentum, or Alfresco (open source) if you are looking for a scalable, enterprise solution.

Any CMS can be used as a news publishing system, but keep in mind that "news publishing system" doesn't mean the same thing to everyone :)
Are you only online, or do you require print options as well?
Need workflow and security?
Translations into different languages or document formats?
How much content do you intend on storing?

We can attempt to narrow down the list if you'd like to add some specific features for which you're looking. But, as your question stands, the options are almost limitless (the price range is too!).